Sub-Sampling

Sub Sampling

In reality, a 5 MHz probe only needs a sampling frequency of 25 MHz. But, instead of lowering the sampling frequency (100 MHz), sub-sampling is used.

1. The sub-sampling rate is chosen at 1 in 4 for a 5 MHz probe. It means that only 1 sample out of 4 will be displayed and recorded
2. Groups of 4 samples are created. The sample with the highest amplitude in the group is kept and placed at the position of the first sample of the group
3. The signal is recreated from the points
4. All digital signals are treated simultaneously

Sub-sampling is a good way to reduce the size of recorded files without the risk of loosing important amplitude peaks.